For 30 minutes on Monday, Deputy Attorney General Rod Rosenstein traded political scrutiny of his duties overseeing special counsel Robert Mueller for judicial scrutiny of his arguments in a criminal sentencing challenge before the U.S. Supreme Court.

Rosenstein, attired in the government’s traditional Supreme Court garb of morning coat and vest—borrowed for the event from the U.S. Solicitor General’s Office—made his first high court appearance, arguing in the case Chavez-Meza v. United States.